Double-diaphragm air-operated pumps are in general well known. Such pumps are generally well-suited for transferring materials out of drums or other bulk storage units to another location. Such pumps should be easily and inexpensively manufactured, easily serviced and compatible with a large variety of materials as well as having long service life. While diaphragms have been formed of materials having ridges thereon, such construction inevitably leads to the increased use of material in return for the desired service life. It is therefore an object of this invention to provide a diaphragm pump which is easily serviced, inexpensively manufactured, and yet provides excellent service life.